[Feature] Komga API Key

[holocronweaver]

It seems Komga supports API keys for authentication.

A quick search of this repo didn't turn up any prior attempts at switching Konf/Komga integration to API keys, so this is a feature request to add support.

For backwards compatibility un/pw authentication could still be supported (maybe deprecated for removal in later releases?).

The main benefits of API keys I can think of:

• avoiding passing un/pw across the network
• being able to revoke 3P integration permissions at a granular level, without requiring user to change their password which would revoke all 3P integration permissions